Disturbance-accelerated succession increases the production of a temperate forest.

Many secondary deciduous forests of eastern North America are approaching a transition in which mature early-successional trees are declining, resulting in an uncertain future for this century-long carbon (C) sink. We initiated the Forest Accelerated Succession Experiment (FASET) at the University of Michigan Biological Station to examine the patterns and mechanisms underlying forest C cycling following the stem girdling-induced mortality of >6,700 early-successional Populus spp. (aspen) and Betula papyrifera (paper birch).

COSORE: A community database for continuous soil respiration and other soil-atmosphere greenhouse gas flux data.

Globally, soils store two to three times as much carbon as currently resides in the atmosphere, and it is critical to understand how soil greenhouse gas (GHG) emissions and uptake will respond to ongoing climate change. In particular, the soil-to-atmosphere CO flux, commonly though imprecisely termed soil respiration (R ), is one of the largest carbon fluxes in the Earth system. An increasing number of high-frequency R measurements (typically, from an automated system with hourly sampling) have been made over the last two decades; an increasing number of methane measurements are being made with such systems as well.

3,4-Methylenedioxypyrovalerone: Neuropharmacological Impact of a Designer Stimulant of Abuse on Monoamine Transporters.

Methylenedioxypyrovalerone (MDPV) is an abused synthetic cathinone, commonly referred to as a "bath salt." Because the dopamine (DA) transporter (DAT) and vesicular monoamine transporter-2 (VMAT-2) are key regulators of both the abuse and neurotoxic potential of structurally and behaviorally related agents, the impact of MDPV on these transporters was investigated. Results revealed that a single in vivo MDPV administration rapidly (within 1 hour) and reversibly increased both rat striatal DAT and VMAT-2 activity, as assessed via [H]DA uptake in synaptosomes and synaptic vesicles, respectively, prepared from treated rats.

Defining a spectrum of integrative trait-based vegetation canopy structural types.

Vegetation canopy structure is a fundamental characteristic of terrestrial ecosystems that defines vegetation types and drives ecosystem functioning. We use the multivariate structural trait composition of vegetation canopies to classify ecosystems within a global canopy structure spectrum. Across the temperate forest sub-set of this spectrum, we assess gradients in canopy structural traits, characterise canopy structural types (CST) and evaluate drivers and functional consequences of canopy structural variation.

Forest aging, disturbance and the carbon cycle.

Contents Summary 1188 I. Introduction 1188 II. Forest aging and carbon storage 1189 III.

Effects of structural complexity on within-canopy light environments and leaf traits in a northern mixed deciduous forest.

Canopy structure influences forest productivity through its effects on the distribution of radiation and the light-induced changes in leaf physiological traits. Due to the difficulty of accessing and measuring forest canopies, few field-based studies have quantitatively linked these divergent scales of canopy functioning. The objective of our study was to investigate how canopy structure affects light profiles within a forest canopy and whether leaves of mature trees adjust morphologically and biochemically to the light environments characteristic of canopies with different structural complexity.

Net primary production of a temperate deciduous forest exhibits a threshold response to increasing disturbance severity.

The global carbon (C) balance is vulnerable to disturbances that alter terrestrial C storage. Disturbances to forests occur along a continuum of severity, from low-intensity disturbance causing the mortality or defoliation of only a subset of trees to severe stand- replacing disturbance that kills all trees; yet considerable uncertainty remains in how forest production changes across gradients of disturbance intensity. We used a gradient of tree mortality in an upper Great Lakes forest ecosystem to: (1) quantify how aboveground wood net primary production (ANPP,) responds to a range of disturbance severities; and (2) identify mechanisms supporting ANPPw resistance or resilience following moderate disturbance.

Joint control of terrestrial gross primary productivity by plant phenology and physiology.

Terrestrial gross primary productivity (GPP) varies greatly over time and space. A better understanding of this variability is necessary for more accurate predictions of the future climate-carbon cycle feedback. Recent studies have suggested that variability in GPP is driven by a broad range of biotic and abiotic factors operating mainly through changes in vegetation phenology and physiological processes.

Sustained carbon uptake and storage following moderate disturbance in a Great Lakes forest.

Carbon (C) uptake rates in many forests are sustained, or decline only briefly, following disturbances that partially defoliate the canopy. The mechanisms supporting such functional resistance to moderate forest disturbance are largely unknown. We used a large-scale experiment, in which > 6700 Populus (aspen) and Betula (birch) trees were stem-girdled within a 39-ha area, to identify mechanisms sustaining C uptake through partial canopy defoliation.

Herbarium specimens reveal the footprint of climate change on flowering trends across north-central North America.

Shifting flowering phenology with rising temperatures is occurring worldwide, but the rarity of co-occurring long-term observational and temperature records has hindered the evaluation of phenological responsiveness in many species and across large spatial scales. We used herbarium specimens combined with historic temperature data to examine the impact of climate change on flowering trends in 141 species collected across 116,000 km(2) in north-central North America. On average, date of maximum flowering advanced 2.

Optimizing wind power generation while minimizing wildlife impacts in an urban area.

The location of a wind turbine is critical to its power output, which is strongly affected by the local wind field. Turbine operators typically seek locations with the best wind at the lowest level above ground since turbine height affects installation costs. In many urban applications, such as small-scale turbines owned by local communities or organizations, turbine placement is challenging because of limited available space and because the turbine often must be added without removing existing infrastructure, including buildings and trees.

15N discrimination and the sensitivity of nitrogen fixation to changes in dietary nitrogen in Reticulitermes flavipes (Isoptera: Rhinotermitidae).

Xylophagous termites possess symbiotic bacteria that fix atmospheric nitrogen (N(2)). Although symbiotic N(2) fixation is central to termite nutrition and ecologically important, it is energetically costly. Using stable isotopes, we tested the hypothesis that symbiotic N(2) fixation would decrease in workers of the eastern subterranean termite, Reticulitermes flavipes Kollar, which were exposed to high nitrogen diets.

Fire effects on temperate forest soil C and N storage.

Temperate forest soils store globally significant amounts of carbon (C) and nitrogen (N). Understanding how soil pools of these two elements change in response to disturbance and management is critical to maintaining ecosystem services such as forest productivity, greenhouse gas mitigation, and water resource protection. Fire is one of the principal disturbances acting on forest soil C and N storage and is also the subject of enormous management efforts.

Ecosystem CO2 fluxes of arbuscular and ectomycorrhizal dominated vegetation types are differentially influenced by precipitation and temperature.

Here, we explore how interannual variations in environmental factors (i.e. temperature, precipitation and light) influence CO(2) fluxes (gross primary production and ecosystem respiration) in terrestrial ecosystems classified by vegetation type and the mycorrhizal type of dominant plants (arbuscular mycorrhizal (AM) or ectomycorrhizal (EM)).

Kinetics of nitrogen uptake by Populus tremuloides in relation to atmospheric CO(2) and soil nitrogen availability.

Sustained increases in plant production in response to elevated atmospheric carbon dioxide (CO(2)) concentration may be constrained by the availability of soil nitrogen (N). However, it is possible that plants will respond to N limitation at elevated CO(2) concentration by increasing the specific N uptake capacity of their roots. To explore this possibility, we examined the kinetics of (15)NH(4) (+) and (15)NO(3) (-) uptake by excised roots of Populus tremuloides Michx.

Neither mycorrhizal inoculation nor atmospheric CO concentration has strong effects on pea root production and root loss.

•  Root responses to elevated CO concentrations, where nutrient demand was expected to be higher than at ambient CO , and possible interactions with mycorrhizal symbionts are reported for pea (Pisum sativum). These are important below-ground components affecting carbon flow into the soil. •  A video-minirhizotron system was used to study root growth in pot-grown mycorrhizal (inoculated with Glomus caledonium) and nonmycorrhizal pea plants at ambient or elevated CO concentrations over 9 wk.

Response of soil biota to elevated atmospheric CO in poplar model systems.

We tested the hypotheses that increased belowground allocation of carbon by hybrid poplar saplings grown under elevated atmospheric CO would increase mass or turnover of soil biota in bulk but not in rhizosphere soil. Hybrid poplar saplings (Populus×euramericana cv. Eugenei) were grown for 5 months in open-bottom root boxes at the University of Michigan Biological Station in northern, lower Michigan.

A meta-analysis of elevated CO effects on woody plant mass, form, and physiology.

Quantitative integration of the literature on the effect of elevated CO on woody plants is important to aid our understanding of forest health in coming decades and to better predict terrestrial feedbacks on the global carbon cycle. We used meta-analytic methods to summarize and interpret more than 500 reports of effects of elevated CO on woody plant biomass accumulation and partitioning, gas exchange, and leaf nitrogen and starch content. The CO effect size metric we used was the log-transformed ratio of elevated compared to ambient response means weighted by the inverse of the variance of the log ratio.

Interacting effects of soil fertility and atmospheric CO on leaf area growth and carbon gain physiology in Populus×euramericana (Dode) Guinier.

Two important processes which may limit productivity gains in forest ecosystems with rising atmospheric CO are reduction in photosynthetic capacity following prolonged exposure to high CO and diminution of positive growth responses when soil nutrients, particularly N, are limiting. To examine the interacting effects of soil fertility and CO enrichment on photosynthesis and growth in trees we grew hybrid poplar (Populus × euramericana) for 158 d in the field at ambient and twice ambient CO and in soil with low or high N availability. We measured the timing and rate of canopy development, the seasonal dynamics of leaf level photosynthetic capacity, respiration, and N and carbohydrate concentration, and final above- and belowground dry weight.

Genotype-specific effects of elevated CO on fecundity in wild radish (Raphanus raphanistrum).

Rising atmospheric CO may lead to natural selection for genotypes that exhibit greater fitness under these conditions. The potential for such evolutionary change will depend on the extent of within-population genetic variation in CO responses of wild species. We tested for heritable variation in CO-dependent life history responses in a weedy, cosmopolitan annual, Raphanus raphanistrum.